The Zebra mussel (scientific name Dreissena polymorpha) is native to the waters of the Black Sea and was inadvertently introduced into the waters of the Great Lakes in the mid 1980s. The maximum size of a Zebra mussel is about 35 millimeters and its shell has a banding of light and dark stripes reminiscent of the coloring of the African Zebra. It is generally believed that the introduction into the Great Lakes first took place near the western tip of Lake Erie, and Zebra mussels were probably brought there on ocean-going ships either attached to their hulls or in off-loaded ballast.
The waters of the Great Lakes proved to be a favorable habitat for Zebra mussels, and their numbers and range increased rapidly. Presently they are found along the shores of the Great Lakes and even in some inland lakes and rivers. Zebra mussels attach themselves to under-water objects with a very effective cement. This cement is called byssus and is associated with byssals threads, which are protein-based strands that the mussels exude.
Unfortunately, the Zebra mussel creates major problems, particularly when present in the huge numbers now encountered. Inlets for drinking water or water for cooling power plants that are placed out into one of the Great Lakes have become nearly blocked with Zebra mussels. Large sums of money and significant effort have been expended to drench the inlets with chlorine or other chemicals to kill the Zebra mussels, and then a staggering effort is expended to remove the dead Zebra mussels. U.S. Pat. Nos. 5,062,967, 5,040,487, and 5,015,395 disclose such methods. The hulls and even propellers of ships and boats plying the Great Lakes become fouled with attached Zebra mussels with resultant reductions in efficiency and increases in the cost of maintanance. Anti-fouling coatings appear to be ineffective. The voracious appetites of, and huge numbers of, Zebra mussels have severely disrupted the aquatic food chain. It has been noted that certain relatively shallow costal waters that were opaque with plankton are now clear. Sport fishing in the Great Lakes is of great economic importance and is likely to be adversely affected by the presence of Zebra mussels.
The need for means to control the number of Zebra mussels and the need for an anti-fouling means for preventing Zebra mussels from attaching themselves to underwater objects is clearly evident. Much work has been carried out with these objectives in mind. However, as far as is known, such work has been performed either by placing substances in the vicinity of wild Zebra mussels present in the Great Lakes or by experimenting on captive Zebra mussels prior to their expiration within some ten days of being removed from the Great Lakes. Hitherto Zebra mussels have not been maintained in captivity in a laboratory setting for extended periods of time. It is well known that research into the control of an organism, whether it is the AIDS virus or the Zebra mussel, is most effectively performed on organisms that are maintained in the laboratory.
Accordingly, the object of the present invention is a method and procedure for maintaining captive Zebra mussels in a healthly state for extended periods.